Protein therapeutic preparations include one or more species of proteins (e.g., differentially post-translationally modified species, different glycoforms, etc.) secreted from cell culture or isolated from a cell's surface as the biologically active ingredient. Alteration of the protein's conformation or aggregation state is known to affect its biological activity, immunogenicity, and biophysical properties. For example, a protein's conformation or aggregation state will affect its ability to interact with a target molecule (e.g., the protein therapeutic erythropoietin with the erythropoietin receptor) as well as its stability (e.g., its susceptibility to precipitation).
Since protein conformations may vary in response to changes in manufacturing conditions, qualitative and/or quantitative assessments of batch homogeneity is important during development and marketing of a protein therapeutic. Assessment of protein preparations during optimization of the manufacturing process is also important. The ability to make comparisons between protein preparations from different sources (e.g., generic vs. FDA approved originator) would also be useful.
There is therefore a need in the art for analytical techniques that can provide a detailed understanding of differences in protein conformation between different protein preparations.